/*
  Red Black Trees
  (C) 1999  Andrea Arcangeli <andrea@suse.de>
  (C) 2002  David Woodhouse <dwmw2@infradead.org>
  (C) 2012  Michel Lespinasse <walken@google.com>

  This program is free software; you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation; either version 2 of the License, or
  (at your option) any later version.

  This program is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with this program; if not, write to the Free Software
  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

  linux/include/linux/rbtree_augmented.h
*/

#ifndef _LINUX_RBTREE_AUGMENTED_H
#define _LINUX_RBTREE_AUGMENTED_H

// #include <linux/compiler.h>
#include "rbtree_base.h"

/*
 * Please note - only struct rb_augment_callbacks and the prototypes for
 * rb_insert_augmented() and rb_erase_augmented() are intended to be public.
 * The rest are implementation details you are not expected to depend on.
 *
 * See Documentation/rbtree.txt for documentation and samples.
 */

struct rb_augment_callbacks
{
    void (*propagate)(struct rb_node *node, struct rb_node *stop);
    void (*copy)(struct rb_node *old, struct rb_node *cnew);
    void (*rotate)(struct rb_node *old, struct rb_node *cnew);
};

extern void __rb_insert_augmented(struct rb_node *node, struct rb_root *root,
                                  void (*augment_rotate)(struct rb_node *old, struct rb_node *cnew));
/*
 * Fixup the rbtree and update the augmented information when rebalancing.
 *
 * On insertion, the user must update the augmented information on the path
 * leading to the inserted node, then call rb_link_node() as usual and
 * rb_augment_inserted() instead of the usual rb_insert_color() call.
 * If rb_augment_inserted() rebalances the rbtree, it will callback into
 * a user provided function to update the augmented information on the
 * affected subtrees.
 */
static inline void
rb_insert_augmented(struct rb_node *node, struct rb_root *root,
                    const struct rb_augment_callbacks *augment)
{
    __rb_insert_augmented(node, root, augment->rotate);
}

#define RB_DECLARE_CALLBACKS(rbstatic, rbname, rbstruct, rbfield,       \
                             rbtype, rbaugmented, rbcompute)            \
    static inline void                                                  \
        rbname##_propagate(struct rb_node *rb, struct rb_node *stop)    \
    {                                                                   \
        while (rb != stop)                                              \
        {                                                               \
            rbstruct *node = rb_entry(rb, rbstruct, rbfield);           \
            rbtype augmented = rbcompute(node);                         \
            if (node->rbaugmented == augmented)                         \
                break;                                                  \
            node->rbaugmented = augmented;                              \
            rb = rb_parent(&node->rbfield);                             \
        }                                                               \
    }                                                                   \
    static inline void                                                  \
        rbname##_copy(struct rb_node *rb_old, struct rb_node *rb_new)   \
    {                                                                   \
        rbstruct *old = rb_entry(rb_old, rbstruct, rbfield);            \
        rbstruct *cnew = rb_entry(rb_new, rbstruct, rbfield);           \
        cnew->rbaugmented = old->rbaugmented;                           \
    }                                                                   \
    static void                                                         \
        rbname##_rotate(struct rb_node *rb_old, struct rb_node *rb_new) \
    {                                                                   \
        rbstruct *old = rb_entry(rb_old, rbstruct, rbfield);            \
        rbstruct *cnew = rb_entry(rb_new, rbstruct, rbfield);           \
        cnew->rbaugmented = old->rbaugmented;                           \
        old->rbaugmented = rbcompute(old);                              \
    }                                                                   \
    rbstatic const struct rb_augment_callbacks rbname = {               \
        .propagate = rbname##_propagate,                                \
        .copy = rbname##_copy,                                          \
        .rotate = rbname##_rotate};

#define RB_RED 0
#define RB_BLACK 1

#define __rb_parent(pc) ((struct rb_node *)(pc & ~3))

#define __rb_color(pc) ((pc) & 1)
#define __rb_is_black(pc) __rb_color(pc)
#define __rb_is_red(pc) (!__rb_color(pc))
#define rb_color(rb) __rb_color((rb)->__rb_parent_color)
#define rb_is_red(rb) __rb_is_red((rb)->__rb_parent_color)
#define rb_is_black(rb) __rb_is_black((rb)->__rb_parent_color)

static inline void rb_set_parent(struct rb_node *rb, struct rb_node *p)
{
    rb->__rb_parent_color = rb_color(rb) | (unsigned long)p;
}

static inline void rb_set_parent_color(struct rb_node *rb,
                                       struct rb_node *p, int color)
{
    rb->__rb_parent_color = (unsigned long)p | color;
}

static inline void
__rb_change_child(struct rb_node *old, struct rb_node *cnew,
                  struct rb_node *parent, struct rb_root *root)
{
    if (parent)
    {
        if (parent->rb_left == old)
            WRITE_ONCE(parent->rb_left, cnew);
        else
            WRITE_ONCE(parent->rb_right, cnew);
    }
    else
        WRITE_ONCE(root->rb_node, cnew);
}

extern void __rb_erase_color(struct rb_node *parent, struct rb_root *root,
                             void (*augment_rotate)(struct rb_node *old, struct rb_node *cnew));

static __always_inline struct rb_node *
__rb_erase_augmented(struct rb_node *node, struct rb_root *root,
                     const struct rb_augment_callbacks *augment)
{
    struct rb_node *child = node->rb_right;
    struct rb_node *tmp = node->rb_left;
    struct rb_node *parent, *rebalance;
    unsigned long pc;

    if (!tmp)
    {
        /*
         * Case 1: node to erase has no more than 1 child (easy!)
         *
         * Note that if there is one child it must be red due to 5)
         * and node must be black due to 4). We adjust colors locally
         * so as to bypass __rb_erase_color() later on.
         */
        pc = node->__rb_parent_color;
        parent = __rb_parent(pc);
        __rb_change_child(node, child, parent, root);
        if (child)
        {
            child->__rb_parent_color = pc;
            rebalance = NULL;
        }
        else
            rebalance = __rb_is_black(pc) ? parent : NULL;
        tmp = parent;
    }
    else if (!child)
    {
        /* Still case 1, but this time the child is node->rb_left */
        tmp->__rb_parent_color = pc = node->__rb_parent_color;
        parent = __rb_parent(pc);
        __rb_change_child(node, tmp, parent, root);
        rebalance = NULL;
        tmp = parent;
    }
    else
    {
        struct rb_node *successor = child, *child2;

        tmp = child->rb_left;
        if (!tmp)
        {
            /*
             * Case 2: node's successor is its right child
             *
             *    (n)          (s)
             *    / \          / \
             *  (x) (s)  ->  (x) (c)
             *        \
             *        (c)
             */
            parent = successor;
            child2 = successor->rb_right;

            augment->copy(node, successor);
        }
        else
        {
            /*
             * Case 3: node's successor is leftmost under
             * node's right child subtree
             *
             *    (n)          (s)
             *    / \          / \
             *  (x) (y)  ->  (x) (y)
             *      /            /
             *    (p)          (p)
             *    /            /
             *  (s)          (c)
             *    \
             *    (c)
             */
            do
            {
                parent = successor;
                successor = tmp;
                tmp = tmp->rb_left;
            } while (tmp);
            child2 = successor->rb_right;
            WRITE_ONCE(parent->rb_left, child2);
            WRITE_ONCE(successor->rb_right, child);
            rb_set_parent(child, successor);

            augment->copy(node, successor);
            augment->propagate(parent, successor);
        }

        tmp = node->rb_left;
        WRITE_ONCE(successor->rb_left, tmp);
        rb_set_parent(tmp, successor);

        pc = node->__rb_parent_color;
        tmp = __rb_parent(pc);
        __rb_change_child(node, successor, tmp, root);

        if (child2)
        {
            successor->__rb_parent_color = pc;
            rb_set_parent_color(child2, parent, RB_BLACK);
            rebalance = NULL;
        }
        else
        {
            unsigned long pc2 = successor->__rb_parent_color;
            successor->__rb_parent_color = pc;
            rebalance = __rb_is_black(pc2) ? parent : NULL;
        }
        tmp = successor;
    }

    augment->propagate(tmp, NULL);
    return rebalance;
}

static __always_inline void
rb_erase_augmented(struct rb_node *node, struct rb_root *root,
                   const struct rb_augment_callbacks *augment)
{
    struct rb_node *rebalance = __rb_erase_augmented(node, root, augment);
    if (rebalance)
        __rb_erase_color(rebalance, root, augment->rotate);
}

#endif /* _LINUX_RBTREE_AUGMENTED_H */
